Struct async_task::Task

pub struct Task<T> { /* fields omitted */ }

A task reference that runs its future.

At any moment in time, there is at most one Task reference associated with a particular task. Running consumes the Task reference and polls its internal future. If the future is still pending after getting polled, the Task reference simply won't exist until a Waker notifies the task. If the future completes, its result becomes available to the JoinHandle.

When a task is woken up, its Task reference is recreated and passed to the schedule function. In most executors, scheduling simply pushes the Task reference into a queue of runnable tasks.

If the Task reference is dropped without getting run, the task is automatically canceled. When canceled, the task won't be scheduled again even if a Waker wakes it. It is possible for the JoinHandle to cancel while the Task reference exists, in which case an attempt to run the task won't do anything.

Methods

impl<T> Task<T>

pub fn schedule(self)

Schedules the task.

This is a convenience method that simply reschedules the task by passing it to its schedule function.

If the task is canceled, this method won't do anything.

pub fn run(self) -> bool

Runs the task.

Returns true if the task was woken while running, in which case it gets rescheduled at the end of this method invocation.

This method polls the task's future. If the future completes, its result will become available to the JoinHandle. And if the future is still pending, the task will have to be woken up in order to be rescheduled and run again.

If the task was canceled by a JoinHandle before it gets run, then this method won't do anything.

It is possible that polling the future panics, in which case the panic will be propagated into the caller. It is advised that invocations of this method are wrapped inside catch_unwind. If a panic occurs, the task is automatically canceled.

pub fn cancel(&self)

Cancels the task.

When canceled, the task won't be scheduled again even if a Waker wakes it. An attempt to run it won't do anything.

pub fn tag(&self) -> &T

Returns a reference to the tag stored inside the task.

pub fn into_raw(self) -> *const T

Converts this task into a raw pointer to the tag.

pub unsafe fn from_raw(raw: *const T) -> Task<T>

Converts a raw pointer to the tag into a task.

This method should only be used with raw pointers returned from into_raw.

pub fn waker(&self) -> Waker

Returns a waker associated with this task.

Trait Implementations

impl<T: Debug> Debug for Task<T>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<T> Drop for Task<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T> Send for Task<T>

impl<T> Sync for Task<T>